The present invention relates generally to short messaging services for cellular phone subscribers to enable cellular subscribers to send and receive short text messages and, more particularly, to a text entry method to enable more rapid entry of text messages.
Short Message Service (SMS) is a service implemented in many cellular systems, including GSM and ANSI/TIA/EIA-136 (ANSI-136) systems that enables cellular subscribers to send and receive short text messages. There are three basic types of messaging servicesxe2x80x94point-to-point messaging, point-to-multi-point messaging, and broadcast messaging. Point-to-point SMS sends a message from a single source to a single receiver. Point-to-multi-point SMS sends a message from a single source to two or more receivers. In both point-to-point and point-to-multi-point messaging, the receiving units are paged by the base station and notified that the message is coming. The receiving unit then tunes to a predetermined messaging channel and waits for the message. In broadcast messaging, the message is broadcast on a predetermined messaging channel to all mobile units monitoring the messaging channel.
Because mobile phones typically have very few keys, originating SMS messages from a mobile unit is a laborious task. One common approach to text entry used in cellular phones is referred to as the multi-tap method. In the multi-tap method, a plurality of alphanumeric characters and symbols are associated with the numeric keys. The numeric keys are pressed multiple times in sequence to cycle through the available characters and symbols associated with that particular key. For example, assume that the letters of the alphabet are assigned to the numeric keys as follows:
In order to enter the word FAST with a trailing space, the user would have to press five different keys with a total of ten separate key presses. The 3-key is pressed three times to enter the letter F, the 2-key is pressed once to enter the letter A, the 7-key is pressed four times to enter the letter S, the 8-key is pressed once to enter the letter T, and the 1-key is pressed once to enter a space.
Using the multi-tap method, the user is required to spell each word, entering one character at a time. The user is required to think about the spelling of each word, key assignments (which character is associated with which key), and the number of times the key needs to be pressed in order to select the desired character. This data entry method is not intuitive and typically requires a large number of key presses. Further, the initial press of each key usually starts a timer and the cursor automatically advances when the timer expires. If the user takes too long cycling to the desired character, the wrong character will be entered. The user then has to press the CLR key and start over.
Another method commonly used for entering text messages into cellular phones is known as predictive typing, such as a method known as T9. Using a predictive typing method, the user enters the first few characters of a word using the numeric keys. For example, to enter the word FAST, the user would press the 3, 2, and 8 keys in sequence. The phone compares the key sequence entered by the user to a stored vocabulary to find matching words. If only a single matching word is found, the remainder of the characters are filled in by the phone. If more than one matching word is found, the user is allowed to scroll through a list of the matching words to select the desired word. Because the words are drawn out of a dictionary based on statistical probabilities and not on an alphabetical ordering, this method is not intuitive, especially for first-time users.
As currently implemented, the SMS service also limits the length of the text message that can be sent or received. For instance, an SMS message in GSM cannot contain more than 140 bytes of data. Since standard ASCII text requires 7 bits per character, text messages are limited to 160 characters. Of course, other systems, such as ANSI-136, may have different size limits for SMS type messages, but similar logic applies. To overcome this problem, protocols have been developed to allow longer text messages to be broken into a plurality of smaller messages, transmitted one at a time and re-assembled at the receiving end. One can refer to the teachings of the GSM and ANSI-136 specifications for exemplary SMS details; however, such details are not necessary for understanding the present invention.
The ability to send text messages is a powerful means of communication. To take full advantage of this service, the process of creating a text message needs to be as quick and efficient as possible. Therefore, there remains much room for improvement of text entry methods suitable for use by cellular subscribers to enter short text messages. Also, it would be desirable to send messages longer than 160 characters.
The present invention is a text entry method for entering short messages into a mobile phone having a limited number of keys. According to the present invention, a word list is stored in a memory. The words in the word list are divided into a plurality of word groups, with each word group being assigned to a particular key, referred to as a group key. For example, the numeric keys on the phone""s keypad can be used as group keys during text entry mode. By convention, standard telephones have letters associated with the numeric keys. The letters DEF are associated with the 3-key on a standard keypad. The present invention includes a word group containing words beginning with DEF and this group is assigned to the 3-key.
To enter a word from the predefined word list into a text message, the user first selects a group key to display one of the word groups. The user can then scroll through the words in the selected word group until the desired word is reached.
In another aspect of the present invention, a plurality of alphanumeric characters and other symbols are divided into character groups. Each character group is assigned to a group key. The user can enter words or symbols that are not in the word list by selecting characters from the character groups. Characters may be selected in the same manner as words by first selecting the character group and then scrolling through the character group to the desired character or symbol.
In another aspect of the present invention, the words and characters are represented in one or more enhanced character sets, each character set including 256 words and characters. Each word or character in the character set is associated with an 8-bit codeword. Using the enhanced character set of the present invention, it is possible to send text messages having more than 160 characters, the current limit in GSM phones using the standard ASCII key character set.
Other objects and advantages will become apparent to those skilled in the art upon a review of the following specification and drawings.